Personal protective equipment for COVID‐19 among healthcare workers in an emergency department: An exploratory survey of workload, thermal discomfort and symptoms of heat strain

Abstract Objectives To examine workload, thermal discomfort and heat‐related symptoms among healthcare workers (HCWs) in an Australian ED during the COVID‐19 pandemic. Methods A cross‐sectional study design was employed among HCWs in an ED at a metropolitan hospital in Brisbane, Australia. Respondents provided demographic information including their self‐reported age, sex, height, weight, role (e.g. doctor, nurse), and whether they wore personal protective equipment (PPE) during their shift, rated as either Full PPE, Partial PPE, or usual uniform or scrubs. The workload of HCWs was assessed with the National Aeronautics and Space Administration's task load index (NASA‐TLX). Thermal discomfort was evaluated using scales from the International Organisation for Standardisation. Responders rated their subjective heat illness using the Environmental Symptoms Questionnaire. Results Fifty‐nine HCWs completed the survey (27 male, 31 female, one prefer not to answer). Overall workload from the NASA‐TLX was 64.6 (interquartile range [IQR] 56.5–73.3) for doctors, 72.5 (IQR 63.3–83.3) for nurses and 66.7 (IQR 58.3–74.17) for other staff, representing moderate to high ratings. Eighty‐one percent reported thermal sensation to be slightly warm, warm, or hot, and 88% reported being uncomfortable, ranging from slightly to extremely. Ninety‐seven percent reported at least one heat‐strain symptom. More than 50% reported light‐headedness or headache and approximately 30% reported feeling dizzy, faint, or weak. Conclusions ED HCWs experience thermal discomfort when wearing PPE. Combined with their workloads, HCWs experienced symptoms related to heat strain. Therefore, careful consideration should be given to managing heat strain among HCWs when wearing PPE in an ED.


Introduction
Personal protective equipment (PPE) is required to protect frontline doctors, nurses and allied health professionals (healthcare workers [HCWs]) from cross-infection. In past epidemics of highly infectious diseases • The majority of HCWs experience thermal discomfort wearing PPE. • More than half of HCWs reported headaches, and >30% felt dizzy or faint.
• Further research into physiological strain, performance and patient outcomes is warranted.
such as Ebola, SARS and Zika, PPE has been critical to protecting HCWs from infection. 1 PPE increases thermal insulation around the body and impairs evaporative heat loss. 2,3 Consequently, wearers may experience thermal discomfort and heat strain including elevated core and skin temperatures, sweat losses, and heart rates. 4 Elevated thermal discomfort from wearing PPE may also impair the performance of complex cognitive tasks. 5 As such, careful consideration should be given to the impacts of PPE among HCWs. Several studies have recently reported aspects of thermal discomfort among HCWs during the COVID-19 pandemic. Internationally, over 50% of HCWs report heat as an adverse effect of PPE. [6][7][8][9] Among HCWs in the UK's National Health Service, the vast majority reported feeling 'hot', were 'very uncomfortable' wearing PPE, and stated that the PPE impaired their physical performance. 5 Almost all surveyed Dutch HCWs reported heat strain symptoms when wearing PPE compared to only 30% when not wearing PPE. 10 In Singapore and India, over three quarters of HCWs experienced excessive sweating, thirst and exhaustion. 11 Several limitations of these studies exist, including the use of a range of questionnaires and scales for workload, thermal discomfort, and heat-related symptoms, with varied levels of validation and standardisation. Moreover, these studies did not focus on HCWs in EDs, nor has a study been conducted on the Australian medical population. Therefore, the present study aimed to examine workload, thermal discomfort, and heat-related symptoms among HCWs in an Australian ED during the COVID-19 pandemic.

Participants
A cross-sectional study design was employed to assess thermal comfort, workload and symptoms of heat strain among emergency and critical care staff at a metropolitan hospital in Brisbane, Australia. All staff were eligible to complete an anonymous online survey at the end of their work shift. Links to the survey were distributed via email and made available in break rooms. Respondents provided demographic information including their self-reported age, sex, height, weight, role (e.g. doctor, nurse), and whether they wore PPE during their shift, rated as either Full PPE (including a gown/apron, an N95 mask, eye protection and gloves), Partial PPE (some, but not all, of the items listed for full PPE), or usual uniform or scrubs. PPE requirements were defined by the Australian Government's contact and droplet precautions guidelines for PPE use in routine care of patients with suspected, probable or confirmed COVID-19. 12 The data collection period occurred during the COVID-19 pandemic and spanned from June 2021 to March 2022. While the environment within the ED was air conditioned (20-24 C), Brisbane summer and winter temperatures (minimum and maximum) in Brisbane average 22-30 C and 10-22 C, respectively. Participants were informed about the survey prior to commencing, and submission of their responses constituted consent to participate. The study was approved by the Mater Misericordiae Ltd. Human Research Ethics Committee (EC00332, project ID 69541). The study is reported in accordance with STROBE guidelines.

Standardised scales and assessments
The survey consisted of scales and indices for evaluating three aspects of heat stress: workload, thermal discomfort and heat strain symptoms. Optionally, participants were also invited to write comments about their experiences wearing PPE during their shift.

Workload
Workload is an important consideration for assessing heat stress, as the physical aspects of work increase metabolic heat production and nonphysical aspects may be exacerbated by heat strain. The National Aeronautics and Space Administration's task load index (NASA-TLX) was used to assess six aspects of staff workload over the shift. 13 As previously described by Hoonakker et al. 14 with intensive care nurses, respondents were asked to rate six subscales on a 20-step scale, resulting in a score from 0 (low) to 100 (high), including physical, mental, and temporal demands, as well as their performance, effort and frustration (Appendix S1). The raw scores were used for analysis, and overall workload (the average of the six subscales) was also calculated for each participant. 14

Thermal discomfort
The International Organisation for Standardisation (ISO) provides comprehensive guidance on assessing the thermal environment in various occupational settings. 15 The guidance aims to identify concerns affecting health and safety and to outline risk management strategies according to the specific context observed. Respondents were asked to answer the questions with respect to how they felt while wearing PPE (or with respect to how they felt wearing their usual scrubs/ uniform). They rated their thermal comfort on a 5-point scale from comfortable to extremely uncomfortable, thermal sensation on a 7-point scale from hot to cold, thermal preference on a 7-point scale from much warmer to much cooler, stickiness (sweatiness) on a 4-point scale from not sweaty to very sweaty, tolerability on a 5-point scale from perfectly tolerable to intolerable, and acceptance as acceptable or unacceptable 15 (Appendix S2).

Heat strain symptoms
The Environmental Symptoms Questionnaire (ESQ) contains a subscale known as the index of subjective heat illness (SHI). 16,17 The ESQ-SHI comprises 22 symptoms related to exertional heat illness that are rated on a 6-point scale from 0 (not at all) to 5 (extreme) (Appendix S3). The sum of each symptom's score is taken as the overall index value. The ESQ-SHI has also been used in other populations wearing PPE including American football players, 18

Results
Fifty-nine ED staff completed the survey (27 male, 31 female, one prefer not to answer), representing a response rate of 41%. Response rates for nurses (n = 18) and doctors (n = 32) were 17% and 94%, respectively. Other staff (n = 9) included allied health professionals, phlebotomists, wards persons and students.
Respondents  (2), P = 0.169). Overall workload did not differ based on sex (w = 451.5, P = 0.199), nor was it related to age (r = 0.830, P = 0.543) or BMI (r = 0.205, P = 0.129). The NASA-TLX revealed moderate to high ratings across all subscales (Fig. 1). Subscale ratings between the roles were not significantly different, with the exception of physical workload (H(2) = 14.97, P < 0.001), for which doctors tended to have lower scores than nurses and other staff.

Thermal discomfort
Overall, staff reported thermal discomfort during their shift (Fig. 2). Eighty-one percent of respondents reported thermal sensation to be slightly warm, warm, or hot, and 88% reported being uncomfortable, ranging from slightly to extremely. While 34% of respondents had a preference to be neither warmer nor cooler, 58% desired to be slightly cooler or cooler. The majority (73%) of respondents reported being sweaty to some degree, mostly slightly. Although 61% described the conditions as slightly difficult to tolerate, only 22% found it unacceptable. The levels of PPE worn showed significant positive relationships with thermal sensation (P = 0.042) and sweatiness (P = 0.023).
Sixteen respondents provided comments about their experience wearing PPE (Table S1). Four comments related to experience of heat, five focused on the impact of the PPE, six described how PPE affected their work practices, and one highlighted how their performance and efficiency was affected.

Discussion
Our exploratory survey confirms that thermal discomfort among Australian HCWs in an ED is very common when wearing PPE (88%). Moreover, moderate to high workloads and heat-related symptoms suggest HCWs are experiencing a level of heat strain. Further research into physiological strain, task performance, and patient care is warranted as effective management practices may be required to avoid excessive strain and performance deterioration.
The SARS-CoV-2 variant has brought about unprecedented challenges for HCWs. Importantly, a number of occupational implications have emerged, including the use of PPE across emergency and critical care settings. EDs are regularly congested, and clinicians frequently must multitask across a range of cognitively and procedurally demanding tasks. As such, there is concern that the ability to perform a range of diagnostic and procedurally demanding tasks optimally may in part be hampered by the application of PPE. 5,10 In the present study, the NASA-TLX demonstrated overall workload among doctors, nurses, and other staff was moderate to high, similar to previous reports among intensive care nurses. 14 Physical and temporal demands add to the thermal burden experienced by HCWs by increasing metabolic heat production, and similar to the physical demands indicated via the NASA-TLX subscale in the present study, a previous study also confirmed moderate to vigorous physical activity among emergency nurses in Australia. 21 Mental demands, effort and frustration, which were rated moderate to high (Fig. 1), may be exacerbated by thermal discomfort and heat strain. In addition, many individual comments related to work practices (Table S1), such as ensuring regular breaks to reduce physical demands and allow for rehydration. For these reasons, and similar to HCWs in the NHS, 5 carefully managing HCW workloads may be an important avenue to mitigate the adverse effects of PPE.
Heat is internationally recognised as a prominent adverse effect for HCWs wearing PPE. [6][7][8][9] While previous research has used a range of scales and questionnaires, we followed the guidance of the ISO to evaluate thermal discomfort. 15 Elevated thermal discomfort is concerning as HCWs have reported adverse effects of wearing PPE on the performance of complex cognitive tasks, impairing their attentional focus, decision making and problem solving abilities. 5 Furthermore, thermal discomfort may degrade infection control because of frequent donning and doffing of PPE, reported among 77% of HCWs in the NHS. 5 Finally, thermal discomfort may be a precursor to heat strain symptoms.
Heat strain symptoms are an indication that the physiological mechanisms regulating body temperature may be compromised. The high proportion of Australian HCWs experiencing heat strain symptoms while wearing PPE in the present study is comparable to similar populations abroad. 5,10,11 Concerningly, more than 50% reported light-headedness or headache and approximately 30% reported feeling dizzy, faint, or weak in the present study. These symptoms may predispose HCWs to accidents and injuries. Furthermore, the median ESQ-SHI in the present study (14.0) was comparable to military personnel successfully completing an outdoor march (mean 15.0), but lower than experienced by personnel who withdraw from the march because of their symptoms (mean 28.4). 20 This comparison highlights that wearing PPE, even in an air-conditioned hospital environment, elevates heat strain comparably to physically demanding outdoor work without PPE. While the present study captures heat-strain symptoms over a single shift, research among outdoor workers in Northern Australia highlights that workers experience a range of moderate to severe heat strain symptoms on daily and weekly bases. 22 Not only do they report the adverse effects of heat on work tasks, but also on their sleep, appetite and relationships with friends and family. 22 Concerningly, regular exposure to heat-strain symptoms from wearing PPE may have adverse effects beyond the workplace.
Not only does the primary focus on reducing contagion risk for HCWs neglect the physiological and cognitive stresses incurred by PPE, but a range of other health concerns also arise. Skin injuries, predominantly facial, are known to occur because of device-related pressure, prolonged moisture retention and skin tears. 23 Furthermore, many HCWs develop PPE-associated headaches or exacerbation of their pre-existing headache disorders, 24 and there are concerns about procedural dexterity and surgical performance being impaired by PPE. 25 Overall, a comprehensive approach should be considered to implement effective management practices that mitigate excessive strain and performance deterioration while ensuring the protection offered by PPE to HCWs.
Several limitations of the present study should be acknowledged. First, the study recruited only a small sample size from a single institution, which may limit the generalisability of the findings. Of note, only four respondents wore usual scrubs (no PPE), thus caution should be exercised when interpreting the relationship found between PPE level and thermal discomfort parameters. Second, the self-report nature of the assessments cannot rule out potential biases from respondents. Third, the cross-sectional design of the study does not enable conclusions to be drawn regarding whether wearing PPE affects task performance and patient outcomes by elevating heat strain in HCWs. However, the level of discomfort and heat-related symptoms reported, coupled with the individual comments suggests a potential impact is concerningly plausible. How and if PPE impacts patient care will need to be explored further through controlled research studies. Such research should objectively measure physiological responses (core and skin temperatures, heart rate and sweat loss) and indicators of task performance alongside perceptual measures when wearing standard scrubs with and without PPE.
In conclusion, ED HCWs experience thermal discomfort when wearing PPE. Combined with their workloads, HCWs experienced symptoms related to heat strain. Therefore, careful consideration should be given to managing heat strain among HCWs when wearing PPE in an ED. Further research into the effects of PPE on performance and patient outcomes is warranted. corresponding author upon reasonable request.